Method1.Combine custard powder, corn flour and castor sugar in a nonstick pan.2.Add milk,butter and stir mixture over low heat until mixed.3.When butter is dissolved, turn heat into medium and keep stirring.4.Gradually adding the egg till mixture thicken.5.Set aside and let cool.6.Spread the filling ontop of the sponge cake and decorate it as desire.7.Cool in the fridge before serving.

Note:If the custard mixture has lumps,immediately pour the custard through a fine sieve into a clean bowl.